on temperature regimes for sanitary outlets
to maintain water hygiene; ensuring the
safe delivery of hot and cold water; how the
correct selection of system components
and correct use by occupants can help
preserve the quality and hygiene of water
supplies, and it provides a point of reference
to legislation, standards and other guidance
pertaining to water systems.
WATER SYSTEMS
The guide contains an overview of some
of the different water systems (including
specific detail on components) and their
safe installation, commissioning, operation
and maintenance, and it provides technical
guidance for typical system layouts and
individual components (example pictured
at right).
In particular, the tap outlet aerator has
become a major focus for concern. A study
published in the February 2014 issue of
the journal of the Society for Healthcare
Epidemiology of America, showed that
research found significantly higher levels
of infectious pathogens in water from taps
with aerators compared to water from
deeper in the plumbing system. The study
said that researchers from the University
of Genoa in Italy studied cold and hot water
samples at two tertiary care hospitals
for a year from taps used by healthcare
professionals. The study assessed growth
of bacteria at both the tap and deeper within
the water distribution system. Cold and hot
water sampling was carried out first with the
aerators in place, and then after disinfecting
and flame-sterilizing the outlet point and
letting the water run for two minutes, to
HOSPITAL & MEDICAL – WATER SAFETY
“Health risks can only be accepted
if proven to be very low”
WCS Group guidance for water safety groups
analyse the microbiological features of
the plumbing system. Researchers found
the total microbial load was up to 10 times
greater when aerators were in place than
after sterilisation and flushing.
Other specific areas considered high risk
include interruptions in water supply. This
can increase the risk of microbial ingress,
especially if these result in depressurisation
of supply pipework. Water system design
should ensure that sufficient reserve
water storage is available to minimise the
consequence of disruption, while at the
same time ensuring an adequate turnover
of water to prevent stagnation in storage
vessels and distribution systems.
Measures to control the spread of
microorganisms in healthcare premises
include the regular use of antimicrobial
hand-rubs. This can result in a significant
reduction in the use of hand-wash basins.
Ensuring water is run regularly to flush out
dead legs is an important part of water
safety management.
The disinfectant residual in the mains
water supply can also have implications.
Under certain conditions, some water
companies alternate the residual levels of
disinfectant in the mains water supply and
the type of disinfectant used (for example,
chlorine and chloramine) between winter
and summer. Healthcare providers should
consider the installation of secondary
disinfection equipment within their own
premises to ensure the safety of supply.
WCS Group’s Chris Abraham says
that his company has produced its own
guidance for WSGs. The document
states that WSGs should follow a set of
fundamental principles, the first being
that no healthcare operation is risk-free,
and health risks can only be accepted if
proven to be very low. In particular, WSGs
must approach water safety as a collective
responsibility. General awareness of the
threat and risks must be made mandatory,
and a level of competence must be
maintained through training and by the use
of outsourced support and partnering with
external hygiene specialists.
A typical water supply system from Health Technical Memorandum 04-01:
Open vent
En-suite Bedroom
Shower
TMV
Mains water in
Toilet Dirty utility
Schematic layout of a cold (and hot) water service system (note: this is a schematic only and therefore
all isolation valves and specific pipework configuration recommendations may not be included)
Bedpan
washer
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June 2019 www.operationsengineer.org.uk 29
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